Water compatibility is a highly significant property of functional fluids and lubricants. The significance of this property is most important under severe conditions such as when the functional fluids and lubricants come into contact with water under extreme pressure and temperature conditions. In the absence of acceptable water tolerance properties, such functional fluids and lubricants will have its lubricating and/or power transmission properties substantially reduced. Accordingly, many manufacturers of equipment requiring the use of functional fluids and lubricants require that such fluids and lubricants contain certain water tolerance properties. For example, manufacturers of agricultural tractor machinery have specific requirements with respect to the tractor fluids used in connection with the machinery; and, such requirements include specific water tolerance properties which the manufacturer believes to be necessary for the equipment to operate successfully under severe conditions.
In addition, the clarity of such functional fluid often impacts greatly on the fluid's marketability. A fluid that is turbid or becomes turbid after a short period of use and exposure to contaminate water, is often unacceptable to consumers regardless of the performance characteristics of the fluid.
U.S. Pat. No. 4,579,672 discloses functional fluids and lubricants having improved water tolerance properties. The compositions are comprised of major amounts of a synthetic or mineral oil of lubricating viscosity with minor amounts of oil soluble alkoxypolyethyleneoxy acid phosphite ester compounds dispersed therein as the water tolerance improving compounds. This patent discusses a number of related patents at columns 1 and 2.
U.S. Pat. Nos. 4,435,297; 4,368,133; 4,329,249; 4,448,703; and 4,447,348 relate to nitrogen-containing phosphorus-free carboxylic acid derivatives. These derivatives are in general made by the reaction of an acylating agent with an alkanol tertiary monoamine. The derivatives described are indicated as being useful in incorporating oil-soluble, water-insoluble functional additives, such as metal salts of acid phosphate and thiophosphate hydrocarbyl esters, into water-based functional fluids such as water-based hydraulic fluids.
U.S. Pat. No. 3,219,666 discloses oil-soluble nitrogen-containing compositions which are indicated as being useful dispersing agents in connection with various lubricants such as crankcase oils, gears, and power transmitting units.
U.S. Pat. No. 4,401,581 discloses lubricating oil dispersants. The dispersants are made by reacting (a) alkenyl succinic anhydride, (b) an alcohol, (c) a hydroxy-substituted amine, (d) polyoxyalkyleneamine, and (e) an alkenyl succinimide.
U.S. Pat. No. 4,225,447 discloses emulsifiable concentrates which are used for water-in-oil fire resistant hydraulic fluids. The concentrate is comprised of a lubricant and a polyalkenylsuccinic acid or anhydride of a salt.
U.S. Pat. No. 3,324,033 discloses oil-soluble lubricating oils having ashless dispersants present therein wherein the ashless dispersants are the reaction product of an alkenyl succinic anhydride and a dethanolamine.
U.S. Pat. No. 4,522,736 discloses compounds which are formed by a reaction involving alkenylsuuccinic anhydrides and aminoalcohols and aromatic secondary amines. The patent also discloses lubricating compositions which contains such reaction products.
U.S. Pat. No. 4,256,595 discloses diesel crankcase lubricant compositions. The compositions include a base oil having therein a 5-amino-triazole-succinic anhydride reaction product. The reaction product is formed by reacting a hydrocarbyl succinic anhydride (in which the hydrocarbyl radical has from 12 to 30 carbon atoms) with 5-amino-triazole.
Japanese Patent Disclosure (Kokai) No. 56-131695 discloses an Anticorrosive Boiling-Point Lowering Preventative Agent containing Boron compounds obtained by dehydrogenation condensation under heating of boric acid with compounds having an amino group and a hydroxyl group.
The present inventor has discovered that improved functional fluids and lubricating compositions can be obtained by combining major amounts of an oil of lubricating viscosity with a minor amount of a water tolerance improving composition. In this respect, the present invention relates to the same general concept which is being carried out in the patents discussed above. However, the compounds which the present inventor utilizes as the water tolerance fix is structurally different from and chemically distinct from the compounds referred to in the above-discussed patents. Although the compounds per se utilized by the present inventor to improve the water tolerance fix properties of the composition are not themselves novel (see U.S. Pat. No. 4,435,297), such compounds as included within oil compositions in the percentage amounts claimed in order to improve water tolerance properties are novel compositions.
U.S. Pat. No. 4,225,447 to Law et al appears to disclose the reaction product of a hydrocarbon substituted succinic anhydride with an N,N-dialkylalkanolamine used as a water tolerance fix in water-in-oil emulsions containing 10-60% water.
The present invention is not an aqueous system or even an oil-in-water emulsion, but rather an oil composition which contains 5% or less of water as a contaminant in the oil composition. Accordingly, in this respect, the present invention is basically different from either the '297 or '447 patents above.
U.S. Pat. No. 4,401,581 to Burrows et al disclosed high molecular weight alkenyl succinic derivatives as effective dispersants in lubricating oils (column 1, lines 8-9). Hydrocarbyl substituents specifically disclosed include polyisobutenyl groups (column 2, lines 25-27). The patent also discloses alkanol amines such as diethanol amine and THAM (see column 2, lines 46-59).